I had a SMALL directory which was an adjunct to my site (not the main focus);
Was it an "add on" to the main site ? or was it a site in it's own right on it's own domain ?
The latter would be better ..linked ( maybe just the one link, of the "If you'd like to know more about "widgets or how to make them" type link ) from the former ..and the directory linking back to the widgets site again, maybe just the once, with a "you can buy high quality widgets here"..
Make the directory site more of a general information "widget how to" site..
And your "widget site" into more of a "commercial and information about widget" site..